Segment Routing is a new technology focusing on addressing pain points of existing multiprotocol label switching networks. Segment routing addresses these pain points by providing source routing (i.e., the transmitting node can define the path of tunnels the packet will take).
However, Segment Routing can run into issues when operating in a Massively Scalable Data Center (MSDC) networks with a large number of end point tunnels utilizing Equal-cost multi-path routing (ECMP). ECMP is a routing strategy where next-hop packet forwarding to a single destination can occur over multiple “best paths” which tie for top place in routing metric calculations. For each Segment Routing tunnel, ECMP needs to allocate unique ECMP objects (i.e., per end-point) to carry the tunnels, even if the ECMP links to be traversed are the same. Accordingly, when Segment Routing tunnel end-points are scaled up, ECMP resources can quickly deplete, crippling the network.